Recent content by K_Mitchell

  1. K

    Laser frequency doubling range for nonlinear crystals

    This is actually a straightforward question, but I'm struggling to find answers because I don't know very much about lasers. I want to use a nonlinear crystal for frequency doubling in an infrared laser (1480 nm) so that the output is half @ 740 nm. I know that nonlinear crystals like KTP are...
  2. K

    Sparking through glass despite being below breakdown voltage

    Now that I don't know unfortunately. I just sent a text to the guy to ask him, and will post his reply if I receive one. We lost contact for about a year.
  3. K

    Sparking through glass despite being below breakdown voltage

    @Baluncore, you're right on the money in your prediction. When bonding pure silicon to glass, this is what I experience: 1) Voltage is cranked up, holds steady for 1-2 minutes 2) voltage starts to plummet, first very quickly to about 1/3 of its highest value, then a bit slower until it bottoms...
  4. K

    Sparking through glass despite being below breakdown voltage

    With those kinds of forces, you're probably doing direct bonding with heat. I've worked on two commercial anodic bonders before, and they had a maximum of around 100 N, but in direct bonding mode this was significantly higher. In my system, I just apply about 15-20 N.
  5. K

    Sparking through glass despite being below breakdown voltage

    I looked at it very carefully just now while using an aluminum cathode I use for bonding smaller pieces. The pitting is much worse when using aluminum vs. graphite and I can see the location of pits very clearly. They are indeed on the top of the glass, where glass meets cathode. My silicon...
  6. K

    Sparking through glass despite being below breakdown voltage

    I'm anodically bonding a 0.5 mm silicon wafer to a 0.5 mm Pyrex 7740 glass wafer. My silicon wafer has a thick layer of oxide on its surface, and because it this insulating layer requires a high voltage to produce a strong bond. The setup that I constructed is illustrated below (using...
  7. K

    Difficult time brazing drill bit to ultrasonic horn

    Thanks for the help. I watched that video, then watched a few more in series. It seems the technique I needed was to heat up the base of the horn for awhile first, otherwise it may act as a heat sink cooling the solder on top too quickly. Once the horn is a dull red, I move up a little more...
  8. K

    Material that can be bent repetitively without fatique?

    Would this be useful? http://en.wikipedia.org/wiki/Nickel_titanium
  9. K

    Difficult time brazing drill bit to ultrasonic horn

    I have an ultrasonic drill, and need to attach a stainless steel drill bit (hollow tube) to a hardened steel horn. For anyone unfamiliar with ultrasonic drilling, please take a look at the following illustration with instructions for mounting the drill bit...
  10. K

    How can I fine tune an ultrasonic frequency?

    I tried getting in touch with the company but no luck. I suppose the only way is to measure the output. If it's 110V, then I guess I can get a step up transformer rated for 400W (a bit higher than I need). In this case, the flow diagram would go like: 110VAC outlet --> 110VAC/300W/28KHz driver...
  11. K

    How can I fine tune an ultrasonic frequency?

    So here's a breakdown of the devices and their voltage/frequency/power: Power source (driver): Rated 110VAC, 28KHz, 300W Transducer: Rated 220VAC, 28KHz, 300W I was planning to plug the 110V PCB driver into a 110V outlet, which is compatible. The 110V driver at 28 KHz and 300W then powers the...
  12. K

    How can I fine tune an ultrasonic frequency?

    Last question for you guys. The transducer is listed as 220V. However, my power source is 110V because my outlet is the same and I don't have a variac. Considering that the transducer is just a chunk of metal and ceramic that vibrates at a certain frequency (28 KHz), then as long as my driver is...
  13. K

    How can I fine tune an ultrasonic frequency?

    Thanks for the help, that's what I was hoping to hear. On a funny side note, I just got off the phone with a company based in CA that sells ultrasonic drills. They had time to talk, so I pitched my idea to them and mentioned that I even had cheap access to a 900W driver. After laughing for a...
  14. K

    How can I fine tune an ultrasonic frequency?

    I'm drilling through two 0.5 mm thick wafers of silicon and glass (1.0 mm total) that are bonded together using a 1000V anodic bonding tool that I built last year. I plan on making 0.8 mm or 1.0 mm diameter holes using hollow drill bits found here and using silver solder to hold them in place as...
  15. K

    How can I fine tune an ultrasonic frequency?

    Thanks for all the input so far. Like Baluncore said, stress (on the horn) can be large, especially for a stepped design and lowering the impedance to my knowledge can help reduce that stress. I've been doing some more searching, and found some items that may make my life a bit easier. I've been...
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